Freshwater Mussels, Snails, and Crayfish of the Upper Farmington River Watershed

Biodrawversity LLC

Report Prepared by: Ethan Nedeau and Paul Low Biodrawversity LLC 441 West Street Amherst, MA 01002

Report Prepared for: Farmington River Coordinating Committee 101 East River Road, PO Box 395 Pleasant Valley, Connecticut 06063 and Massachusetts Natural Heritage and Endangered Species Program Route 135 Westborough, MA 01581

ABSTRACT

Biodrawversity LLC surveyed freshwater mussels, snails, and crayfish in the West Branch Farmington River, Still River, Sandy Brook, and Clam River in Connecticut and Massachusetts. Fifty-six sites were surveyed on 12 days between May 30 and September 6, 2007. Surveyors recorded information on the distribution, abundance, demographics, shell condition, and habitat of freshwater mussels, as well as the distribution and habitat of snails and crayfish. Seventeen species were found, including six freshwater mussels, eight snails, and three crayfish. Habitat was generally not ideal for snails and only two species—Amnicola limosa and Ferrissia rivularis—were widespread. Crayfish were present in many locations; Cambarus robustus was the most common species. The West Branch and its coldwater tributaries support several of the finest eastern pearlshell populations in southern New England, a species of special concern in Connecticut whose populations rely on trout and salmon populations and excellent water quality. The West Branch also supports a regionally important population of the brook floater, a species that is endangered in Massachusetts and Connecticut. Three mussel species—brook floater, triangle floater, and creeper—appear to be imperiled or highly imperiled in the West Branch and Still River based on low numbers of animals, lack of reproduction, poor condition of animals, or limited habitat. Relevant threats to these species or their habitat are identified in this report. The report recommends long-term monitoring to (1) periodically assess the abundance, demographics, and condition of animals at reference sites, and (2) to identify and address threats as they emerge. The report recommends other actions that will help protect and restore aquatic biodiversity in the upper Farmington River.

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Sandy Brook at survey site SB-8 along Sandy Brook Road in Colebrook, CT. (September 2007)

INTRODUCTION ment. In 2007, the FRCC engaged Biodrawversity LLC to conduct freshwater mussel, snail, and crayfish surveys The West Branch Farmington River (hereafter called the in the Wild and Scenic portion of the West Branch, lower West Branch) is perhaps the most valuable recreational Still River, and Sandy Brook. river and coldwater fishery in southern New England. In 2005 and 2006, freshwater mussel surveys were Fourteen miles of the West Branch in Connecticut, down- conducted in the lower Farmington River with fund- stream of the Goodwin Dam, is part of the National Wild ing from the U.S. Fish and Wildlife Service, The Nature and Scenic River System. Each year, tens of thousands of Conservancy, and the Connecticut Department of Envi- kayakers, tubers, canoeists, anglers, and wildlife watchers ronmental Protection (CT-DEP) (Nedeau 2005, Nedeau enjoy its clean cold water and well-protected upland land- 2006a, Nedeau 2006b). These studies determined that the scape. The Massachusetts portion of the West Branch is Farmington River supports the highest diversity of mus- eligible for, but not included in, the National Wild and sels in southern New England and a globally significant Scenic River System. It is, however, vital to the health of population of the federally endangered dwarf wedgemus- the lower river. Major tributaries that affect the health of sel (Alasmidonta heterodon). Eleven of 12 mussel species these waters include the Still River, Sandy Brook, Mad native to southern New England occur in the Farmington River, and Clam River. River—diversity matched in New England only by the As part of the implementation of the Upper Farm- 410-mile Connecticut River itself. This intact mussel as- ington River Management Plan, which is coordinated by semblage is an urgent conservation priority and provided the Farmington River Coordinating Committee (FRCC), critical justification for the inclusion of the lower Farming- various studies have been conducted on instream flows, ton River in the National Wild and Scenic River System. bank and channel condition, invasive plants, water qual- Mussel studies in the lower Farmington River left ity, fisheries, and biodiversity. These studies help to define questions about how far upstream these populations oc- conservation targets and guide protection and manage- cur in the Farmington River and whether important mus-

Freshwater Mussels, Snails, and Crayfish of the Upper Farmington River Watershed www.biodrawversity.com sel assemblages occur in principal tributaries. The brook groups of animals in New England. Six of the 12 species floater, which is listed as Endangered in Massachusetts and native to Connecticut, and seven of 12 native to Mas- Connecticut, was known to occur in the Massachusetts sachusetts, are listed as endangered, threatened, or special portion of the West Branch. The Massachusetts Natural concern and therefore receive state or federal protection Heritage and Endangered Species Program (MNHESP) (Nedeau et al. 2000, Nedeau and Victoria 2003). There contributed funds to the FRCC project so that more in- is a critical need to discover populations of endangered tensive studies of the brook floater in Massachusetts could mussels in order to protect them. Endangered species can be conducted and to provide watershed-wide context for provide justification for protecting riparian corridors and these species (crossing political boundaries). This report instream habitat, assessing and removing stream barriers, combines data from the FRCC and MNHESP studies. restoring fisheries, and implementing the most protective Freshwater mussels are ecologically important animals Best Management Practices (BMPs) for projects that may that are sensitive to habitat alteration and water quality, degrade river conditions (Nedeau 2008). and are used to assess the health of waterbodies (Nedeau et An interesting aspect of the life history of freshwa- al. 2000, Nedeau 2008). They are one the most imperiled ter mussels is that larvae are obligate external parasites of

Table 1. Nomenclature, habitat, range, and fish hosts of freshwater mussels known to occur in the Farmington River watershed. Distribution based on this survey and Nedeau (2005, 2006a, and 2006b). See Nedeau 2008 for additional information.

Species General Habitat Farmington River Watershed Host Species Eastern Pearlshell Small streams and small rivers; mainly Sparse or absent in lower Farmington Atlantic salmon, brook trout, brown trout, Margaritifera margaritifera coldwater habitats; inhabits a variety of River (Farmington to Windsor); present rainbow trout substrates in riffles, runs, and pools in West Branch and in several coldwater tributaries Triangle Floater Small streams to large rivers; rarely in Present throughout the Farmington River Common shiner, blacknose dace, longnose Alasmidonta undulata lakes; inhabits a variety of substrates watershed and several tributaries dace, pumpkinseed sunfish, fallfish, slimy and flow conditions sculpin, white sucker, largemouth bass Brook Floater Small streams and small rivers; mainly Confined to Massachusetts portion of Longnose dace, blacknose dace, slimy Alasmidonta varicosa cold or coolwater habitats; inhabits the West Branch in Otis and Sandisfield; sculpin, golden shiner, pumpkinseed sand, gravel, and cobble in riffles and not known from any tributaries sunfish, yellow perch, margined madtom runs Dwarf Wedgemussel Small streams to large rivers; inhabits a Present in lower Farmington River from Tesselated darter, slimy sculpin, possibly Alasmidonta heterodon variety of substrates and flow conditions Avon to upper end of Rainbow Dam juvenile Atlantic salmon impoundment Creeper Small streams to large rivers; inhabits a Found sporadically in lower river from Creek chub, longnose dace, blacknose Strophitus undulatus variety of substrates and flow conditions Rainbow Dam impoundment to Farming- dace, white sucker, pumpkinseed sunfish, ton; rare in upper watershed largemouth bass, fallfish, golden shiner, common shiner, yellow perch, slimy sculpin Eastern Floater Small to large rivers and lakes; mainly Rare in Farmington River and West Generalist: Warmwater species (probably Pyganodon cataracta cool or warmwater habitats; prefers Branch, except for Massachusetts por- sunfish, bass, and perch) lentic or depositional habitats tion of West Branch; probably common in lakes and ponds Alewife Floater Small to large rivers and coastal lakes Found sporadically between Avon and American shad, alewife, blueback herring Anodonta implicata with anadromous (clupeid) fisheries; the Rainbow Dam impoundment; more inhabits a variety of substrates and flow common near mouth of Connecticut conditions River Eastern Elliptio Habitat generalist; abundant in most Present throughout the Farmington River Generalist Elliptio complanata permanent aquatic habitats watershed and several tributaries; rare in high-gradient coldwater streams Eastern Pondmussel Small to large rivers and lakes; primarily Present in lower Farmington River from Unknown: anadromous or with a coastal Ligumia nasuta coastal or within reach of anadromous Farmington to the Connecticut River affinity; possibly banded killifish fish; inhabits a variety of substrates and flow conditions Tidewater Mucket Small to large rivers and lakes; primarily Found only in low-gradient waters near Anadromous or with a coastal affinity; Leptodea ochracea coastal or within reach of anadromous the mouth of the river possibly white perch, striped bass, alewife, fish; inhabits a variety of substrates and yellow perch flow conditions Eastern Lampmussel Small to large rivers and lakes; mainly Present in lower Farmington River from Generalist: Warmwater species (probably Lampsilis radiata cool or warmwater habitats; inhabits a Farmington to the Connecticut River sunfish, bass, and perch) variety of substrates and flow conditions

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Table 2. Nomenclature and habitat of snails and crayfish collected STUDY AREA during this survey.

Species General Habitat The study area included the Wild & Scenic portion of the SNAILS West Branch in Connecticut (Canton to Hartland), the Family Hydrobiidae: Found on rocks and other submerged objects West Branch and Clam River in Massachusetts (Otis and Amnicola limosa in lakes, ponds, streams, and rivers Sandisfield), the lower Still River (Winchester, Colebrook, Family Viviparidae: A burrowing species that inhabits lakes and and Barkhamsted), and Sandy Brook (Colebrook, CT and Campeloma decisum ponds but may be found in slow rivers, usually in sand or silt near banks and submerged logs Sandisfield, MA) (Figure 1). Representative reaches, and Family Ancylidae: Restricted to streams and rivers where it areas most likely to support high species richness and rare Ferrissia rivularis grazes algae on the surfaces of rocks and species, were chosen based on topographic maps, aerial other submerged objects photographs, field reconnaissance, and best professional Family Planorbidae: Each of these three species are fairly common Helisoma anceps and widely distributed in rivers and lakes in judgment. Fifty-six sites were surveyed in Sandy Brook Planorbella trivolvis Connecticut, usually less common in small (ten sites plus York Lake), Still River (five sites), West Micromenetus dilatatus coldwater rivers Branch in Massachusetts (19 sites), Clam River in Mas- Family Lymnaeidae: Mainly found in lakes and ponds in Pseudosuccinia columella Connecticut but does occur in slow streams sachusetts (one site), and West Branch in Connecticut (20 Family Physidae: Common in permanent aquatic habitats, sites) (Table 3). Physa heterostropha usually on rocks and organic debris Physa sp. (juvenile) METHODS CRAYFISH Family Cambaridae: C. robustus is not native; it is prevalent in Cambarus robustus large rocky streams with moderate current. Two surveyors spent 12 days (from late May to early Sep- Orconectes limosus O. limosus is native and occurs in rivers and tember, 2007) surveying the Still River (1.5 days), Sandy Orconectes virilis lakes of varying sizes. O. virilis is not native and occurs in a variety of permanent aquatic Brook (2.5 days), and West Branch (four days in Con- habitats throughout southern New England. necticut and four days in Massachusetts). Surveyors spent an average of 1.8 person-hours per site (range: 0.5 to four freshwater fish—larvae attach to the fins or gills of fish hours). All sites were surveyed using masks and snorkels, until they metamorphose into free-living juveniles. Mus- and in addition, many sites were surveyed using clear-bot- sels can be specific about which species of fish they will tom buckets and aquatic D-nets. Mussels were identified, parasitize. For example, the eastern pearlshell will only counted, and measured in the field and all were released use salmonids (brook trout, Atlantic salmon, brown trout, unharmed. At 19 sites (but not within the Massachusetts and rainbow trout). Thus, the distribution, abundance, portion of the West Branch), snails and crayfish were col- and dynamics of freshwater mussel populations are closely lected using an aquatic D-net and hand-picked while tied to that of their host fish (Nedeau 2008). Table 1 sum- snorkeling; representative specimens were preserved in al- marizes habitat, distribution, and host fish of freshwater cohol and identified under a dissecting microscope. Snails mussels in the Farmington River watershed. and crayfish were identified using keys of Jokinen (1983, Snails and crayfish were also inventoried for this 1992), Burch and Yung (1992), Peckarsky et al. (1995), project to better characterize the stream fauna. Agen- and Smith (1995). Snails and crayfish were surveyed qual- cies and other groups that monitor stream health, such itatively and this report provides presence-absence data as the Department of Environmental Protection in Con- only. These taxa were not surveyed at every site because necticut and Massachusetts, generally do not sample these it was time consuming to collect them and to process and and other non-insect taxa as rigorously as aquatic insects. identify samples. The crayfishCambarus robustus was not- Table 2 profiles the snails and crayfish encountered during ed where it occurred but was not always collected because this survey. killing that many specimens seemed needless. Based on results of the survey and a summary of pop- Mussel surveys were, with a few exceptions, com- ulation status, habitat, and threats, this report discusses prised of one to four 30-minute timed searches at each opportunities for research and monitoring, conservation, site. Timed searches provide an index of relative abun- and management. dance that can help identify source populations, habitat preference, and distribution patterns. In this report, timed search data are pooled for each survey site. The following data were recorded separately for each 30-minute search:

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Figure 1. The Farmington River watershed of Connecticut and Massachu- MA A-S (19 sites) setts, showing locations of survey sites. See Table 3 and Appendix 1 for details. CR = Clam River, SB = Sandy Brook, SR = Still River; CT-x indicate sites in the West Branch in Connecticut and MA-x indicate sites in the West Branch in Massachusetts. Specific site locations for the Massachusetts portion of the West Branch (MA-A to MA-S) are not shown here.

5 Miles

SB-1 CR-1

SB-2 MA SB-3, SB-4 CT SB-5 MA

SB-6 SB-7 CT

SB-8 SB-9

SB-10 CT-1 SB-11, SR-3 SR-4 CT-2 SR-2 SR-5 CT-3 SR-1 CT-4 CT-5 CT-6 CT-7 CT-8 CT-9 CT-10 CT-11 CT-12 CT-13 CT-14 CT-15 CT-16 CT-17 CT-18

CT-19 CT-20

Connecticut River

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Table 3. Locations of survey sites in Sandy Brook, Still River, Clam River, and West Branch. Location information for the survey sites in the Mas- sachusetts portion of the West Branch are removed and their order has been randomized; people interested in this information should contact the Massachusetts Natural Heritage and Endangered Species Program. See Appendix 1 for site descriptions.

CODE WATERBODY LONGITUDE LATITUDE TOWN COUNTY STATE DATE SB-1 York Lake -73.1822 42.0953 New Marlborough Berkshire MA 5/31/2007 SB-2 Sandy Brook -73.1525 42.0554 Sandisfield Berkshire MA 6/8/2007 SB-3 Sandy Brook -73.1374 42.0441 Sandisfield Berkshire MA 5/31/2007 SB-4 Sandy Brook -73.1369 42.0436 Sandisfield Berkshire MA 5/30/2007 SB-5 Sandy Brook -73.1295 42.0365 Norfolk Litchfield CT 6/7/2007 SB-6 Sandy Brook -73.1119 42.0140 Colebrook Litchfield CT 5/30/2007 SB-7 Sandy Brook -73.0888 42.0107 Colebrook Litchfield CT 6/7/2007 SB-8 Sandy Brook -73.0602 41.9909 Colebrook Litchfield CT 5/30/2007 SB-9 Sandy Brook -73.0529 41.9894 Colebrook Litchfield CT 6/7/2007 SB-10 Sandy Brook -73.0455 41.9780 Colebrook Litchfield CT 5/31/2007 SB-11 Sandy Brook -73.0375 41.9714 Colebrook Litchfield CT 9/6/2007 SR-1 Still River -73.0580 41.9328 Winchester Litchfield CT 6/7/2007 SR-2 Still River -73.0490 41.9466 Winchester Litchfield CT 6/7/2007 SR-3 Still River -73.0375 41.9714 Colebrook Litchfield CT 9/6/2007 SR-4 Still River -73.0311 41.9666 Colebrook Litchfield CT 5/31/2007 SR-5 Still River -73.0201 41.9597 Barkhamsted Litchfield CT 6/7/2007 MA-A WB Farmington River Otis Berkshire MA 6/14/2007 MA-B WB Farmington River Otis Berkshire MA 6/15/2007 MA-C WB Farmington River Otis Berkshire MA 6/8/2007 MA-D WB Farmington River Otis Berkshire MA 6/14/2007 MA-E WB Farmington River Otis Berkshire MA 6/15/2007 MA-F WB Farmington River Sandisfield Berkshire MA 7/10/2007 MA-G WB Farmington River Otis Berkshire MA 6/15/2007 MA-H WB Farmington River Otis Berkshire MA 7/10/2007 MA-I WB Farmington River Otis Berkshire MA 6/14/2007 MA-J WB Farmington River Otis Berkshire MA 6/14/2007 MA-K WB Farmington River Otis Berkshire MA 6/14/2007 MA-L WB Farmington River Otis Berkshire MA 6/14-15/2007 MA-M WB Farmington River Otis Berkshire MA 7/10/2007 MA-N WB Farmington River Otis Berkshire MA 6/8/2007 MA-O WB Farmington River Otis Berkshire MA 7/10/2007 MA-P WB Farmington River Sandisfield Berkshire MA 7/10/2007 MA-Q WB Farmington River Otis Berkshire MA 6/15/2007 MA-R WB Farmington River Otis Berkshire MA 7/10/2007 MA-S WB Farmington River Otis Berkshire MA 6/15/2007 CR-1 Clam River -73.08694 42.09461 Sandisfield Berkshire MA 9/6/2007 CT-1 WB Farmington River -73.01915 41.97868 Hartland Hartford CT 7/5/2007 CT-2 WB Farmington River -73.01756 41.96247 Barkhamsted Litchfield CT 7/5/2007 CT-3 WB Farmington River -73.01339 41.95374 Barkhamsted Litchfield CT 7/5/2007 CT-4 WB Farmington River -73.01318 41.94220 Barkhamsted Litchfield CT 7/5/2007 CT-5 WB Farmington River -73.00072 41.93293 Barkhamsted Litchfield CT 7/5/2007 CT-6 WB Farmington River -73.00245 41.92999 Barkhamsted Litchfield CT 7/2/2007 CT-7 WB Farmington River -73.00312 41.92755 Barkhamsted Litchfield CT 7/2/2007 CT-8 WB Farmington River -72.99381 41.91919 Barkhamsted Litchfield CT 7/2/2007 CT-9 WB Farmington River -72.98908 41.91719 Barkhamsted Litchfield CT 9/6/2007 CT-10 WB Farmington River -72.98675 41.90804 Barkhamsted Litchfield CT 7/2/7007 CT-11 WB Farmington River -72.98688 41.89992 Barkhamsted Litchfield CT 7/26/2007 CT-12 WB Farmington River -72.98039 41.89192 New Hartford Litchfield CT 7/26/2007 CT-13 WB Farmington River -72.98162 41.88802 New Hartford Litchfield CT 7/26/2007 CT-14 WB Farmington River -72.97696 41.87909 New Hartford Litchfield CT 7/2/2007 CT-15 WB Farmington River -72.96469 41.87819 New Hartford Litchfield CT 7/26/2007 CT-16 WB Farmington River -72.95394 41.86676 New Hartford Litchfield CT 7/3/2007 CT-17 WB Farmington River -72.95721 41.86000 New Hartford Litchfield CT 7/3/2007 CT-18 WB Farmington River -72.95571 41.84973 New Hartford Litchfield CT 7/26/2007 CT-19 WB Farmington River -72.95227 41.84284 New Hartford Litchfield CT 7/3/2007 CT-20 WB Farmington River -72.94877 41.84259 New Hartford Litchfield CT 7/3/2007

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• Tallies for each species. At some sites, we estimated Table 4. Counts or estimates of each mussel species found at each numbers of eastern elliptio and eastern pearlshell if site (see Table 3). Cells shaded green are those where abundance was estimated to nearest 100 for survey duration. P = present and not they were very abundant and distracted us from find- counted or estimated. Species abbreviations use the first two letters ing rarer species. of the genus and species name (see Table 1); MaMa = eastern pearl- • Shell lengths for all, or a representative subset of, east- shell, ElCo = eastern elliptio, AlUn = triangle floater, AlVa = brook floater, StUn = creeper, PyCa = eastern floater. ern pearlshells, triangle floaters, brook floaters, and creepers. Length data were used to create length his- Freshwater Mussels tograms that were used to assess recruitment, survi- CODE MaMa ElCo AlUn AlVa StUn PyCa SB-1 0 0 0 0 0 0 vorship, and possible population trends. SB-2 3 200 0 0 0 0 • Shell condition (degree of shell erosion) for each SB-3 15 200 0 0 0 0 SB-4 500 10 0 0 0 0 eastern pearlshell, triangle floater, brook floater, and SB-5 0 0 0 0 0 0 creeper. Shell erosion was subjectively ranked as low SB-6 200 0 0 0 0 0 SB-7 29 0 0 0 0 0 (0), medium (0.5) or high (1.0) for each animal and SB-8 13 0 0 0 0 0 then averaged for all individuals at a site or within a SB-9 1 0 0 0 0 0 SB-10 1 1 0 0 0 0 river. The degree of shell erosion provided insight into SB-11 7 1 0 0 0 0 the integrity of shells and the expected longevity of an SR-1 0 2 0 0 0 0 SR-2 0 3 0 0 0 0 animal. SR-3 7 1 0 0 0 1 • Depth and substrate for each triangle floater, brook SR-4 15 5 0 0 0 0 SR-5 4 0 1 0 0 0 floater, and creeper. MA-A 0 300 0 0 0 P MA-B 0 200 0 5 0 0 MA-C 2 100 0 9 0 0 Notes on habitat and water quality conditions, presence MA-D 0 300 3 1 0 P of fish, water temperature, and other relevant observa- MA-E 0 3 0 0 0 0 MA-F 75 3 0 2 0 0 tions were recorded for each survey site (Appendix 1). MA-G ------Location was recorded using a handheld GPS, and several MA-H 13 0 0 0 0 0 MA-I 0 300 4 0 0 P digital photographs of habitat and biota were taken. Most MA-J 0 300 1 0 0 P MA-K 0 300 0 0 0 0 of the information is contained within this report or in MA-L 0 300 34 24 0 P Appendix 1; additional photographs and raw data can be MA-M 20 25 0 0 0 0 MA-N 0 500 2 23 0 P requested from the primary author. Location information MA-O 8 18 0 10 0 0 for survey sites in the Massachusetts portion of the West MA-P 91 0 0 0 0 0 MA-Q 0 300 0 1 0 0 Branch, where the state-endangered brook floater was MA-R 3 2 0 0 0 0 found, are not included in this report. People interested MA-S 0 300 1 5 3 0 CR-1 50 0 0 0 0 0 in location information for the brook floater should con- CT-1 0 0 0 0 0 0 tact the MNHESP. CT-2 1 0 0 0 0 0 CT-3 30 1 1 0 0 0 CT-4 18 1 4 0 1 3 RESULTS AND DISCUSSION CT-5 61 0 9 0 0 0 CT-6 7 0 0 0 0 0 CT-7 6 0 0 0 0 0 I. Mussels: Distribution CT-8 39 0 14 0 0 0 CT-9 200 0 8 0 0 0 Six mussel species were found during this survey (Table CT-10 38 1 1 0 0 0 4). The highest number of species (five) was found in CT-11 31 0 3 0 0 0 CT-12 1 0 0 0 0 0 the Massachusetts portion of the West Branch; four spe- CT-13 100 0 0 0 0 0 cies were found in the Connecticut portion of the West CT-14 54 0 0 0 0 0 CT-15 103 0 0 0 0 0 Branch and Still River, and two species were found in CT-16 5 0 0 0 0 0 Sandy Brook. Together, the eastern pearlshell and eastern CT-17 19 0 0 0 0 1 CT-18 40 1 4 0 0 0 elliptio comprised 96.9 percent of all mussels encountered CT-19 10 0 0 0 0 0 during this survey, which may be a slight underestimate CT-20 105 0 2 0 0 0 Sandy Brook 769 412 0 0 0 0 because accurate counts were not feasible in areas where Still River 26 11 1 0 0 1 these species were abundant. Although both species were MA West Branch 212 3251 45 80 3 P locally abundant and far outnumbered other species, their CT West Branch 868 4 46 0 1 4 Clam River 50 0 0 0 0 0 dominance was inversely related to each other. Sites gen-

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1000 ale)

100 0-minute Search (log sc er 3

s P 10 Mussel Count

1 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 AB CD EF GH IJ KL MN OP QR S 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

3 ss chne Ri

es 2

Mussel Speci 1

0 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 AB CD EF GH IJ KL MN OP QR S 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Sandy Brook Still River West Branch & Clam River West Branch (Connecticut) SB-1 to SB-11 SR-1 to SR-5 (Massachusetts); MA-A to MA-S, CR-1 CT-1 to CT-20

Location

Figure 2. (a) Number of mussels (all species) counted or estimated per 30-minute interval at survey sites; actual counts or estimates are provided in Table 4. (b) Number of mussel species observed at each survey site; species are listed in Table 4. Data for Sandy Brook, Still River, and West Branch in Connecticut are arranged in order from upstream to downstream, whereas data for the West Branch in Massachusetts is arranged randomly.

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One of the brook floater sites in the West Branch in Massachusetts. (June 2007) erally fell into three categories based on the mussel com- the transition to a pearlshell-dominated community. munity: (1) sites with very low overall mussel abundance, A total of 923 mussels were counted (or estimated) in (2) sites with high mussel abundance, dominated by east- the Connecticut portion of the West Branch. The eastern ern pearlshell, and with low numbers of any other spe- pearlshell comprised 94 percent (868 animals) of the to- cies, or (3) sites with high mussel abundance, dominated tal, followed by the triangle floater (five percent; 46 ani- by eastern elliptio, and with low to moderate numbers of mals), eastern elliptio and eastern floater (0.43 percent; other species. Figures 2 and 3 illustrate mussel diversity four animals each), and creeper (0.1 percent; one dead and abundance patterns for the entire study area. animal). Mussels were sparse or absent in the reach be- Sites with highest mussel diversity (four species) were tween Goodwin Dam and Route 20, and their abundance in the Massachusetts portion of the West Branch, except further downstream was highly variable and patchy. These for one location in the Connecticut portion (CT-4) where patches were often located along stable protected banks, four species were found. Except for CT-4, these sites oc- at downstream ends of islands, and at downstream ends of curred in stream reaches classified as “warmwater” and long pools just prior to the start of another riffle. Riffles, where the eastern elliptio was the dominant species. From deeper portions of pools (toward the middle and upstream Hayden Pond to Tolland State Forest (Otis), the mus- ends), and areas with strong current and rocky substrates sel community was comprised of eastern elliptio, brook supported the fewest number of mussels. Because mus- floater, triangle floater, creeper, and eastern floater. Of the sel distribution and abundance was very patchy, 30-min- more than 3000 eastern elliptio counted or estimated in ute timed searches may not have effectively characterized the entire West Branch, all but four were found in a ten- their abundance and distribution because 30 minutes was mile reach in Otis, Massachusetts. All brook floaters, all sometimes too little time to find a patch of mussels. but four eastern floaters, and three of four creepers were Only 39 mussels were found at five sites in the Still also found in this same reach. The eastern pearlshell was River. Five eastern elliptio were found at sites SR-1 and absent throughout that same reach; it first appeared near SR-2 during surveys of 1.5 hours and 2.5 hours, respec- Tolland State Forest and it became the dominant species tively. This represents extremely low densities; to put this as the river flowed into a high-gradient segment near Cold into context, approximately 300 eastern pearlshell were Spring Campground. Other species disappeared during tallied during a 30-minute timed search in Sandy Brook.

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Upper portion of West Branch in Massachusetts Low gradient reach with warm water and pond/wetland influence. Moderate to high abundance of mussels, dominated by eastern elliptio. Relatively high species richness, including nearly all brook floater occurrences.

Lower portion of West Branch in Massachusetts and lower Clam River High gradient reach with cooler water, rocky substrates, and very little wetland influence. Low to moderate mussel abundance, dominated by eastern pearlshell. Low species richness.

Upper portion of Sandy Brook in Massachusetts Low gradient reach with warmer water and extensive pond and wetland influence. Low to moderate mussel abundance, dominated by eastern elliptio. Low species richness.

Lower portion of Sandy Brook in Massachusetts and Connecticut and Still River from Sandy Brook confluence to West Branch Low to high gradient reaches with cooler water temperatures, rocky substrates, and shallow water. Some wetland MA influence in upper portion, but highly confined rocky channel in lower portion. Low to high mussel abundance, CT dominated by eastern pearlshell.

Upper portion of Still River to Sandy Brook confluence Low to high gradient reach with warmer water, some pond and wetland influence, and more degraded conditions. Mussels sparse or absent; eastern elliptio the most common species.

West Branch in Connecticut Low to high gradient reach with unnaturally cold water, little pond or wetland influence, rocky substrates, and variable depth (more than 12 feet in places). Low to moderate mussel abundance, often with localized high-density patches of eastern pearlshell. Eastern pearlshell dominant, species richness generally low.

Figure 3. General patterns freshwater mussel diversity, abundance, and habitat in the study reaches.

Though habitat seemed appropriate for mussels at SR-1 4 and SR-5, including one old triangle floater at SR-5. and SR-2 (especially the latter), the scarcity of mussels We looked for a survey site in and upstream of Winsted suggests historic habitat degradation or water quality but the river was small, difficult to access, and it seemed problems that the mussels have not yet recovered from. highly altered/impaired by land use in the area between The mussels found at SR-3, which included seven east- Torrington Road and Route 8. Broken glass, old scrap ern pearlshell, were precisely at the confluence of Sandy metal, bricks, and other types of trash and debris at SR- Brook and were probably more within Sandy Brook water 1 and SR-2, together with the appearance of the river at than within Still River water. Mussels were sparse at SR- sites further upriver and the smell of the river downstream

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were found at Sites SB-2 and SB-3 (SB-1 was York Lake in Sandisfield State Forest where no mussels were found). The transition from a mussel community dominated by eastern elliptio to one dominated by eastern pearlshell occurred abruptly less than one mile downstream of Rood Hill Road (about one mile upstream of the border between Connecticut and Massachusetts), where the stream exited a low-gradient reach that was strongly influenced by wetlands and entered a confined, high-gradient, and heavily forested reach. At SB-4, several hundred yards downstream, more than 300 eastern pearlshell were found in a 30-minute search, at least 200 more were found in the next 30-minute search, and densities exceeded 100 per square meter in some spots. Of the 769 eastern pearlshell The transition from a elliptio-dominated community to a pearlshell- dominated community in Sandy Brook occurred approximately here counted or estimated in Sandy Brook, nearly 96.5 percent (SB-3), where the stream exited a low-gradient reach with extensive were found at four sites (SB-4, SB-6, SB-7, and SB-8). wetlands and entered a high-gradient forested reach. Further downstream, Sandy Brook was a high gradient and rocky stream, particularly along Sandy Brook Road, and provided very little mussel habitat even though water quality seemed very good.

II. Mussels: Demographics and Condition Data on demographics and shell condition were collected for the eastern pearlshell, triangle floater, brook floater, and creeper. The creeper was too rare to characterize demographics or condition. Eastern elliptio and eastern floater, the two most common species in the Connecticut River watershed, are discussed later.

Eastern Pearlshell: A total of 677 eastern pearlshells were measured. Shell condition was recorded during the first part of the survey, but it was evident that nearly all of the eastern pearlshell exhibited very little shell erosion and we stopped recording that data. Length data were assessed on a site-by-site basis and then pooled for the four major river segments (Still River, Sandy Brook, West Branch in Mas- High-density patch of eastern pearlshell from Sandy Brook. sachusetts, West Branch in Connecticut). Table 5 provides length statistics for eastern pearlshell. Length-frequency of the wastewater treatment plant, suggest a long history histograms for the major river segments are shown in Fig- of habitat degradation and poor water quality. ure 4. Although Table 5 shows data for the Still River, Sandy Brook supported very high densities of the too few eastern pearlshell were found in the Still River eastern pearlshell, far exceeding abundances that were for a rigorous analysis. Since juvenile eastern pearlshells observed anywhere in the West Branch. Like the up- generally bury themselves in the sediment, and our survey stream parts of the study area in the West Branch, the methods would have only detected animals visible at the upper reaches of Sandy Brook were fairly low-gradient, surface, lack of small eastern pearlshells (>30 millimeters) warmwater environments that flowed through a series of in our dataset is not evidence of poor recruitment. Two wetlands and small ponds. Eastern elliptio were abundant points are important: in upper portions of this watershed; of the 412 elliptio 1. In Sandy Brook and the Connecticut portion of the counted or estimated in Sandy Brook, 400 (97 percent) West Branch, the eastern pearlshell was locally abun-

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Table 5. Length data and size class distribution of eastern pearlshell at sites throughout the study area. Discrepancies between actual counts (Table 4) and data provided here are because only a portion of eastern pearlshell were measured.

Length Data (mm) Length Classes (%) Site Count Average StDev Min Max <20 21-40 41-60 61-80 81-100 101-120 121-140 SB-2 3 113.0 5.6 108 119 0.0 0.0 0.0 0.0 0.0 100.0 0.0 SB-4 37 93.1 19.1 37 122 0.0 2.7 2.7 10.8 43.2 35.1 5.4 SB-6 37 93.9 22.9 47 131 0.0 0.0 16.2 10.8 21.6 45.9 5.4 SB-7 29 74.8 32.4 30 126 0.0 17.2 31.0 3.4 17.2 17.2 13.8 SB-8 13 74.8 32.2 27 114 0.0 23.1 15.4 7.7 30.8 23.1 0.0 SB-9 1 57.0 - 57 57 0.0 0.0 100.0 0.0 0.0 0.0 0.0 SR-3 7 99.6 19.4 76 121 0.0 0.0 0.0 14.3 42.9 28.6 14.3 SR-5 3 83.7 14.0 70 98 0.0 0.0 0.0 33.3 66.7 0.0 0.0 MA-C 2 83.5 10.6 76 91 0.0 0.0 0.0 50.0 50.0 0.0 0.0 MA-F 18 113.1 27.6 37 138 0.0 5.6 0.0 11.1 11.1 11.1 61.1 MA-H 13 118.2 17.4 69 131 0.0 0.0 0.0 7.7 7.7 23.1 61.5 MA-O 8 124.4 6.0 116 131 0.0 0.0 0.0 0.0 0.0 25.0 75.0 MA-P 37 75.7 16.8 46 100 0.0 0.0 24.3 32.4 43.2 0.0 0.0 MA-R 3 116.7 16.6 99 132 0.0 0.0 0.0 0.0 33.3 33.3 33.3 CT-2 1 103.0 - 103 103 0.0 0.0 0.0 0.0 0.0 100.0 0.0 CT-3 22 105.5 16.7 62 125 0.0 0.0 0.0 13.6 18.2 45.5 22.7 CT-4 18 110.3 20.0 56 128 0.0 0.0 5.6 11.1 0.0 50.0 33.3 CT-5 20 101.5 19.6 62 130 0.0 0.0 0.0 10.0 40.0 25.0 25.0 CT-6 7 76.1 34.6 42 133 0.0 0.0 42.9 28.6 0.0 14.3 14.3 CT-7 6 99.7 24.6 60 128 0.0 0.0 16.7 0.0 33.3 33.3 16.7 CT-8 39 65.7 16.4 51 128 0.0 0.0 48.7 38.5 7.7 0.0 5.1 CT-10 38 77.4 23.7 31 126 0.0 10.5 18.4 26.3 26.3 13.2 5.3 CT-11 31 87.0 27.4 29 137 0.0 12.9 3.2 16.1 35.5 25.8 6.5 CT-12 1 91.0 - 91 91 0.0 0.0 0.0 0.0 100.0 0.0 0.0 CT-13 22 90.5 25.9 32 136 0.0 4.5 13.6 9.1 36.4 27.3 9.1 CT-14 54 84.4 26.4 31 134 0.0 9.3 11.1 24.1 18.5 31.5 5.6 CT-15 65 87.4 21.2 36 133 0.0 1.5 6.2 29.2 36.9 20.0 6.2 CT-16 5 82.0 31.8 52 117 0.0 0.0 40.0 20.0 0.0 40.0 0.0 CT-17 19 88.5 21.3 56 137 0.0 0.0 5.3 36.8 26.3 26.3 5.3 CT-18 40 87.6 17.0 48 120 0.0 0.0 2.5 40.0 37.5 20.0 0.0 CT-19 10 97.6 25.6 67 139 0.0 0.0 0.0 30.0 30.0 20.0 10.0 CT-20 68 82.9 25.0 36 136 0.0 5.9 11.8 30.9 27.9 13.2 10.3 River Summary Sandy Brook 120 87.1 26.9 27 131 0 7.5 15.8 8.3 27.5 34.2 6.7 Still River 10 94.8 18.8 70 121 0 0.0 0.0 20.0 50.0 20.0 10.0 West Branch (MA) 81 97.4 28.0 37 138 0 1.2 11.1 19.8 25.9 9.9 32.1 West Branch (MA, minus MA-P) 44 115.6 21.8 37 138 0 2.3 0.0 9.1 11.4 18.2 59.1 West Branch (CT) 466 86.5 24.6 29 139 0 4.1 12.2 26.0 26.4 22.1 9.0

dant, it exhibited strong recruitment (though areas with juveniles were highly patchy), and adult survi- vorship was high. Even the largest animals had very little shell erosion. 2. In the Massachusetts portion of the West Branch, the eastern pearlshell exhibited symptoms of a population with poor recruitment. MA-P was somewhat anomalous and Table 5 separates this from the other sites. Eastern pearlshells from survey sites other than MA- P were, on average, significantly larger than mussels from other portions of the watershed. The length-frequency histogram was strongly skewed toward larger animals (Figure 4). We found only one animal that Eastern pearlshell from Sandy Brook. was less than 68 millimeters long.

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Triangle Floater: A total of 80 triangle floaters were mea- 100 Sandy Brook 90 sured (of the 92 found during this survey). Forty-five of

80 these were from the Massachusetts portion of the West

70 Branch, 34 were from the Connecticut portion of the

60 West Branch, and one was from the Still River. Except for

50 one site in Massachusetts, numbers were too low at any ercent P 40 34.2 site to analyze length data on a site-by-site basis, thus data 30 27.5 were pooled. Table 6 provides length and shell condition

20 15.8 statistics for the triangle floater. The following points are 8.3 10 7.5 6.7 important: 0 0 1. The triangle floater population at the Massachusetts 100 West Branch (MA) site with the highest number of animals (MA-L) ex- 90 hibited symptoms of poor recruitment. These 34 ani- 80 mals were, on average, more than 15 millimeters larger 70 than the 34 triangle floaters collected in the Connect- 60 icut portion of the West Branch (53.4 vs. 38.2) and 50

ercent more than 9 millimeters larger than triangle floaters P 40 32.1 found at other sites in Massachusetts (53.4 vs. 44.1). 30 25.9 19.8 The smallest triangle floater collected at MA-L was 20 11.1 9.9 43 millimeters, and only three triangle floaters from 10 0 1.2 the entire West Branch in Connecticut were larger. 0 100 The length-frequency histogram was strongly skewed West Branch (MA) minus site MA-P 90 toward larger animals.

80 2. Triangle floaters exhibited a high degree of shell ero-

70 sion, especially at MA-L (0.88) and the entire West 59.1 60 Branch in Connecticut (0.83). Each can be explained 50 differently. High shell erosion at MA-L was probably ercent P 40 due to natural shell erosion that comes with old age, 30 since these animals were all very old. High shell ero- 18.2 20 sion in the Connecticut portion of the West Branch 11.4 9.1 10 2.3 was probably due to water chemistry (low pH and 0 0 0 limited calcium availability) and heavy scour that can 100 West Branch (CT) afflict even young animals that should otherwise be in 90 better condition. 80

50 ercent

P 40

30 26.0 26.4 22.1 20 12.2 9.0 10 4.1 0 0 <20 21-40 41-60 61-80 81-100 101-120 121-140 Length Class (mm)

Figure 4. Length class data for eastern pearlshell pooled by major rivers or river segments. The same data are shown in Table 5.

A fairly young but heavily eroded triangle floater typical of animals observed in the West Branch in Connecticut.

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Table 6. Length data and shell condition of the triangle floater in the West Branch in Massachusetts and Connecticut. Discrepancies between actual counts (Table 4) and data provided here are because not all triangle floaters were measured.

West Branch (MA) West Branch (MA) West Branch (MA) West Branch (CT) Parameter All Sites Site MA-L Except MA-L All Sites All Sites Length Statistics Count 45 34 11 34 80 Average 51.1 53.4 44.1 38.2 45.7 Standard Deviation 6.9 5.2 6.9 4.7 8.8 Min 33 43 33 22 22 Max 63 63 53 49 63 Length Classes (percent) <20 0.0 0.0 0.0 0.0 0.0 21-30 0.0 0.0 0.0 2.9 1.3 31-40 8.9 0.0 36.4 61.8 31.3 41-50 31.1 26.5 45.5 32.4 31.3 51-60 55.6 67.6 18.2 0.0 32.5 61-70 4.4 5.9 0.0 0.0 2.5

Shell Condition 0.81 0.88 0.59 0.83 0.82

Brook Floater: A total of 80 brook floaters were measured due to natural shell erosion that comes with old age, at nine different locations in the Massachusetts portion of since these animals are all very old. the West Branch. Table 7 provides length and shell condi- 3. It is interesting to note that MA-L supported both tion statistics for the brook floater. The following points the highest number of brook floaters and the highest are important: number of triangle floaters, but both species at this 1. The brook floater population at the site with the high- site exhibited symptoms of a geriatric population that est number of animals (MA-L) exhibited symptoms of had been unable to recruit new individuals and whose poor recruitment. These 24 animals were, on average, surviving animals were very old and heavily eroded. 19.3 millimeters larger than the 56 brook floaters col- Determining the causes for this should be a conserva- lected elsewhere in the West Branch (67.3 vs. 48.0). tion priority. The length-frequency histogram was strongly skewed toward larger animals and all but two animals were Creeper: Only three live creepers were encountered dur- larger than 63 millimeters, which is near the maxi- ing this survey and all were in the West Branch in Massa- mum published size for the species. chusetts (Site MA-S). The length of these animals was 65 2. The brook floater population at MA-L exhibited ex- mm, 55 mm, and 51 mm. All had a light degree of shell tremely poor shell condition (0.81), especially com- erosion and were found in less than two feet of water in a pared to brook floaters from other locations in the sandy and gravelly substrate. One dead animal was found West Branch (0.33). High shell erosion is probably in the West Branch in Connecticut.

A large and heavily eroded brook floater from the West Branch in A small creeper that exhibits light shell erosion. Massachusetts.

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Table 7. Length data and shell condition of the brook floater in the West Branch in Massachusetts.

West Branch (MA) West Branch (MA) West Branch (MA) Parameter All Sites Site MA-L Only Except MA-L Length Statistics Count 80 24 56 Average 53.8 67.3 48.0 Standard Deviation 12.1 7.9 8.5 Min 32 41 32 Max 79 79 72 Length Classes (percent) <20 0.0 0.0 0.0 21-30 0.0 0.0 0.0 31-40 15.0 0.0 21.4 41-50 31.3 8.3 41.1 51-60 21.3 0.0 30.4 61-70 22.5 62.5 5.4 71-80 10.0 29.2 1.8

Shell Condition 0.48 0.81 0.33

III. Mussels: Species Status Triangle Floater: Imperiled This section recommends the status of each species in the Legal Status: not listed in CT, Special Concern in MA study area based on distribution, abundance, demograph- Based on low overall abundance, a highly patchy distri- ics, shell condition, and habitat. Recommendations apply bution, a high degree of shell erosion that presumably only to this watershed and can be considered in water- limits longevity, and possible reproductive failure at the shed-level conservation and management. These recom- best site in the West Branch in Massachusetts (MA-L), mendations should not be confused with statewide status the triangle floater population is at risk in the study area. in Massachusetts and Connecticut—the CT-DEP and Better populations exist in the lower Farmington River MNHESP list species as Special Concern, Threatened, or between Rainbow Reservoir and Farmington (Nedeau Endangered based on statewide data. To avoid confusion, 2005, 2006a), and elsewhere in Connecticut. Its rarity in this report uses the terms stable, imperiled, or highly im- the West Branch in Connecticut may be related to the un- periled to describe each species. naturally cold thermal regime that limits the distribution of warmwater fish hosts and that is physiologically chal- Eastern Pearlshell: Stable lenging for the species. Legal Status: Special Concern in CT, not listed in MA The upper West Branch and its tributaries support several Brook Floater: Highly Imperiled of the healthiest eastern pearlshell populations in southern Legal Status: Endangered in CT and MA New England. The species relies on salmonid hosts (brook Though the brook floater in the West Branch seems to trout, brown trout, rainbow trout, and Atlantic salmon) be faring better than other known populations in Mas- and is therefore confined to high-quality coldwater riv- sachusetts and Connecticut, its abundance is very low, its ers. Its abundance and distribution in the West Branch is distribution is highly patchy, reproductive failure seems to anomalous in southern New England because the West be an issue, and shell erosion is high. This population is a Branch is such a large river, but the release of cold water high conservation priority in Massachusetts. from Goodwin Dam created a thermal environment that favored trout and the eastern pearlshell. Special manage- Creeper: Highly Imperiled ment of trout waters and efforts to restore Atlantic salmon Legal Status: not listed in CT, Special Concern in MA will likely contribute to the long-term viability of the east- The West Branch and portions of the Still River provide ern pearlshell in the upper West Branch and elsewhere in suitable habitat for this species. Its rarity should be cause Connecticut. for concern, especially since the Farmington River is such a large and relatively intact watershed that supports healthy populations of so many other species. The creeper

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Deep-release water from the West Branch Reservoir through Goodwin Dam creates a unnaturally cold thermal environment that persists for 12-15 miles downstream, creating an excellent coldwater fishery but fragmenting habitat for non-adapted species. was also rarely encountered in the lower Farmington River Eastern Floater: Stable between Windsor and Canton. It occurs infrequently in Legal Status: not listed in CT or MA many rivers in Connecticut and usually at low population None were found in Sandy Brook and very few were densities. If the Farmington River population is indica- found in the Still River or the West Branch in Connecti- tive of its distribution and status elsewhere in Connecti- cut. Though not counted or measured, many were found cut, then it should be evaluated for possible listing under in the low-gradient portion of the West Branch between Connecticut’s Endangered Species Act. Route 8 and Hayden Pond in Massachusetts, which is more typical habitat for this species. Its rarity elsewhere in Eastern Elliptio: Stable the study area is not cause for concern because this species Legal Status: not listed in CT or MA generally prefers large warmwater rivers and lakes—habi- Very few animals were found in lower Sandy Brook, Still tats that were poorly represented during this survey. River, or the Connecticut portion of the West Branch. Based on small population sizes in these waters, popu- IV. Snails lation viability of the eastern elliptio is considered very low. However, it is very abundant in the upper portions Eight species of snails were collected during this survey of Sandy Brook and the West Branch, as well as the lower (Table 8). Amnicola limosa was the numerically dominant Farmington River near Farmington and Avon. This obser- snail and was found at ten of 19 survey sites (six of seven vation follows a pattern observed elsewhere in the Con- sites in the West Branch, one of five sites in the Still River, necticut River watershed that the species tends to be more and three of seven sites in Sandy Brook). This tiny snail abundant in low gradient warmwater rivers than in high- (less than five millimeters) was frequently abundant on gradient coldwater rivers (Nedeau 2008). The release of rocks and submerged logs, especially in calmer waters near cold water from Goodwin Dam, which keeps the West streambanks and in pools. They were particularly abun- Branch cold throughout the summer, may have eradicated dant in the upper portion of Sandy Brook (SB-1 to SB-3). this species from the West Branch and prevents it from It is likely that this species existed virtually everywhere in recolonizing this portion of the river. the study area but concerted effort would be needed to

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Table 8. Snails and crayfish collected during this survey.

Sandy Brook (SB-) Still River (SB-) West Branch in Connecticut (CT-) Taxa 1 2 3 4 5* 6 7* 8 10 1 2 3 4 5 1* 2* 4* 6 7* 8 9* 10 14 16 19 20 Snails Amnicola limosa x x x x x x x x x x Campeloma decisum x x Ferrissia rivularis x x x x x x x x x x Helisoma anceps x Micromenetus dilatatus x Planorbella trivolvis x x x Physa heterostropha x x x x x Physa sp. (young) x Pseudosuccinnia columella x Crayfish Cambarus robustus x x x x x x x x x x x x x x x Orconectes limosus x x x x x Orconectes virilis x x x *Snails and crayfish not collected butCambarus robustus noted if seen. find it in marginal habitats (e.g., rocky erosional environ- color, and since adults lack many natural predators, large ments). Since the species is very common and widespread adults were often seen sitting on the bottom of the river in Connecticut (Jokinen 1983), and therefore not a spe- not trying to hide. Juveniles and small adults were often cies of concern, we did not attempt to find it everywhere. under rocks, logs, and other hiding places. We began to The other common snail species was the limpet Ferris- feel guilty about killing these large animals, and since they sia rivularis, which was also found at ten of 19 survey sites. were quite conspicuous, we stopped collecting them and This species was found on rocks and submerged logs, in tried to note where we saw them. The species was observed both erosional and depositional environments. It is gener- at every location in Sandy Brook except SB-1 (York Lake) ally confined to streams and rivers throughout its North and SB-2 (a low-gradient warmwater site). The species American range (Jokinen 1983). It was rarely abundant, was observed at every location in the Still River down- and it likely occurred throughout the entire study area. stream of the Sandy Brook confluence, and at several sites Like Amnicola limosa, this species is very common and in the West Branch including the site closest to Goodwin widespread, and therefore we did not attempt to find it Dam (CT-1). everywhere. Cambarus robustus is not native to New England; it The other six species of snails were rarely encoun- was introduced sometime in the early twentieth century tered. Generally, rocky coldwater rivers support a lower (Smith 1995). It prefers large rocky streams with moderate diversity and abundance of snails than most other per- current, thus its presence in the West Branch, Still River, manent aquatic habitats, so the lack of snails in our study and Sandy Brook was expected. The ecological effects of area was not a surprise. Snails were much more common this large non-native predator are unknown, but in gen- and diverse in the upper West Branch in Massachusetts, especially downstream of Hayden Pond, but snails were not collected in Massachusetts waters. Lakes, wetlands, vernal pools, swamps, marshes, and low-gradient streams (especially with a warmer thermal regime) in the upper Farmington River watershed likely support more species than the waterbodies that were surveyed in this study.

V. Crayfish

Three species of crayfish were collected during this survey (Table 8). Cambarus robustus was the most common species; it was collected at seven of 19 survey sites but it was noted at 15 sites and probably occurred at many more sites. These large robust animals were often bluish in Cambarus robustus from Sandy Brook.

17 Freshwater Mussels, Snails, and Crayfish of the Upper Farmington River Watershed www.biodrawversity.com eral, crayfish are predators of snails and juvenile mussels and may regulate mollusk populations in areas where they are abundant. Orconectes limosus is native to the Connecticut River watershed. It was found in the Still River (three sites), Sandy Brook (one site), and West Branch (one site). Smith (1995) notes that the species is most frequently found in large rivers and streams with weak to moderate current. Orconectes virilis is not native and was found in York Lake (SB-1) and two sites in the Still River. Smith (1995) con- siders it the most common species in Massachusetts; it occurs in nearly every type of permanent aquatic habitat. Crayfish are tolerant of moderate water quality im- pairment and are adaptable to a variety of habitat conditions (Thorp and Covich 1991). They have good ability to disperse within watersheds and quickly establish populations in suitable areas. Adults are often immune to most aquatic predators, especially in smaller waterbodies where most fish are small-bodied omnivores. Muskrat, otter, and some wading birds might eat them but this predation usually has insignificant effects on crayfish populations. For these reasons, this report does not make any conservation or management recommendations for crayfish.

SUMMARY OF THREATS

The following is a summary of threats that may be relevant for mussels, snails, and crayfish in the study area. Survey site SR-5 in the Still River during normal spring flows (June) The term “threat” is used to describe something that may and baseflow conditions (early September). Extensive dewatering have significantly affected, or has the potential to affect, helps to explain scarcity of mussels encountered during the June the distribution, abundance, and viability of species via survey. the quantity and quality of water and habitat, the ability of a species to reproduce and disperse, and the health and • High predation of mussels by scavengers survival of individuals. In general, the study area provides • Large dewatered areas where mussels either perished or exemplary habitat and water quality, and biological diver- were forced into small refugia (if they could move) sity is less “threatened” here than in many other rivers in • Accumulation of silt due to a lack of flushing flows southern New England. • Excessive algal growth due to warm water temperatures and concentrated nutrients Flow Regime: Periods of low flow may be a significant • Warm water temperatures that approached or exceed- problem for aquatic fauna in some portions of the West ed the thermal tolerance of some species (primarily in Branch, Still River, and Sandy Brook. This was particu- the Massachusetts portion of the West Branch) larly evident in 2007 when drought conditions persisted throughout the summer and rivers were near or below his- Persistent droughts might cause water resource managers toric low levels. Problems seemed to be mainly confined to seek a balance between human demands for water (rec- to the Still River, Sandy Brook, Massachusetts portion of reation and consumption) and the ecological flows needed the West Branch, and other small tributaries. Many of the to maintain fisheries and aquatic biodiversity in these riv- sites surveyed during normal flows in May and June were ers (Trout Unlimited 2006). This might lead to difficult significantly dewatered by September. Associated- prob compromises; in that case, a study of the instream flow lems observed in 2007 include: needs of fish and aquatic invertebrates would be needed.

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More than 90 percent of the eastern pearlshell observed in this small pool in Sandy Brook (SB-4) in early June, which was one of the highest concentrations of the species encountered anywhere in the upper Farmington River watershed, were eaten by a predator by early September. Piles of animals were left behind, each with the posterior end of its shell broken so the predator could pry open the shells.

Dams: The Colebrook Lake Project likely had a signifi- of mussels in the West Branch in Connecticut is low com- cant effect on the freshwater mussel fauna of the West pared to diversity in the lower Farmington River. Branch by permanently fragmenting the river and creat- The possible failure of Hayden Pond Dam in Otis ing a thermal regime that only favored coldwater species. could have catastrophic consequences for the brook floater The extraordinary freshwater mussel diversity in the lower population in the West Branch. The stone dam is located Farmington River declined precipitously in the reach be- just upstream of Ed Jones Road whose crossing is com- tween Farmington and Canton, as the eastern pearlshell, prised of three large culverts. If the dam were breached, which comprised a tiny fraction of the mussel community it would likely destroy that stream crossing and send a in downstream areas, became the dominant species in the pulse of sediment and debris downstream into brook colder waters of the West Branch. The presence of the floater habitat. The Massachusetts Office of Dam Safety eastern pondmussel in Highland Lake in Winchester, and has posted signs to keep people away from the dam. the absence of this species in the Farmington River be- Nonpoint source pollution (NPS): Although much of tween Hartland and Farmington, provides some evidence the land area within the study area is protected, and the that species typically found in warmwater environments river itself is fiercely protected as southern New England’s and that occur in the lower Farmington River—such as finest coldwater fishery, NPS can stem from myriad loca- the eastern lampmussel, eastern floater, eastern elliptio, tions in the watershed and have locally important effects dwarf wedgemussel, and eastern pondmussel—may have on the rivers. Primary problems may include sediment been eradicated (or nearly so) when the West Branch was from roadways and construction sites, stormwater runoff converted to a coldwater river. Nevertheless, the West from urban areas, road salt and snow dumping practices, Branch is a regionally important coldwater fishery and inadequate or failed septic systems, leachate from landfills provides an important source of drinking water to many and disposal sites, and nutrients (primarily nitrogen and of Connecticut’s citizens. This perspective on mussels is phosphorus) from a variety of nonpoint sources and point only offered to help people understand why the diversity sources (such as wastewater treatment plants). Rapid ur-

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The old stone dam at the outlet of Hayden Pond in Otis, Massachusetts, is a decrepit structure that may fail. The Massachusetts Department of Dam Safety prohibits trespassers because of safety concerns. Its failure would likely have short-term yet catastrophic effects on downstream areas, and possibly threaten populations of the endangered brook floater. banization in nearby Granby, Simsbury, Avon, and Can- Beavers: Beavers are a natural and integral part of the eco- ton is likely to spread into this area and put additional system and should not necessarily be viewed as a threat. pressure on its natural resources. Nevertheless, they are particularly active in the upper West Branch in Massachusetts and the large dams that are be- Non-native species: Notable non-native species in the ing built tend to fragment flows, create dispersal barriers, study area include common reed (Phragmites australis) reroute and divide the stream channel, create depositional in wetlands along much of the upper Sandy Brook, two environments upstream, and increase water temperatures. crayfish, smallmouth bass in the upper West Branch, and Mussels are susceptible to some of these effects, and since brown trout and rainbow trout throughout most of the mussels are already faring poorly in this area (especially study area. The common reed likely has locally impor- the brook floater and triangle floater), the effects of bea- tant effects on the ecology of Sandy Brook and its ad- vers may be significant. Beavers may also help to stabilize jacent wetlands. The effects of the non-native crayfishes streamflows in these areas, which might be beneficial for are unknown, but they are large benthic predators that mussels. consume snails and juvenile mussels. Smallmouth bass, brown trout, and rainbow trout may eat or compete with native fish. However, trout are a conservation target and also serve as hosts for the eastern pearlshell, so they are not considered a threat.

20 Freshwater Mussels, Snails, and Crayfish of the Upper Farmington River Watershed www.biodrawversity.com

The West Branch at site CT-13. A sizeable population of eastern pearlshell existed at the downstream end of this large pool and near the tip of an island.

CONCLUSIONS AND RECOMMENDATIONS lower Farmington River, it plays a pivotal role in the vital- ity of the globally important freshwater mussel assemblage The West Branch and its coldwater tributaries support sev- in the lower river. With regard to the conservation and eral of the finest eastern pearlshell populations in southern management of freshwater mussels in the West Branch New England, a species of special concern in Connecti- and its tributaries, this report recommends the following: cut whose populations rely on trout and salmon populations and excellent water quality. The West Branch also 1. Develop a long-term monitoring program for the tri- supports an important population of the brook floater, angle floater, brook floater, and eastern pearlshell in an endangered species in Massachusetts and Connecticut. the West Branch and for the eastern pearlshell in the Three species—brook floater, triangle floater, and creep- Still River and Sandy Brook. The goals should be to er—appear to be imperiled or highly imperiled in the (1) periodically assess the abundance, demographics, West Branch and Still River. Although species diversity and condition of animals at reference sites, and (2) to is low in the West Branch compared to the lower Farm- identify and address new threats as they emerge. ington River, four of six species that occur in the West 2. Delineate important and sensitive areas based on pres- Branch, Still River, and Sandy Brook are sensitive to envi- ence of rare species or their host fish, connectivity be- ronmental stressors and are therefore good candidates for tween populations, and their contribution to critical long-term monitoring. Since the West Branch contributes ecosystem processes. Work with landowners, towns, significantly to the quantity and quality of water in the and others to identify threats and protect these areas.

21 Freshwater Mussels, Snails, and Crayfish of the Upper Farmington River Watershed www.biodrawversity.com

It goes without saying that the health of the West Branch and its tributaries are already a high priority for many natural resource agencies, non-government environmental organizations, citizen groups, and particularly the people who live along it or enjoy what it offers. With all of these people already vested in the Farmington River watershed, protection of its aquatic biodiversity should be successful.

LITERATURE CITED

Burch, J.B., and Y. Jung. 1992. Freshwater snails of the University of Michigan Biological Station area. Walkerana 6(15) Jokinen, E.H. 1983. The Freshwater Snails of Connecticut. State Geological and Natural History Survey of Connecticut Bulletin 109, Department of Environmental Protection, Hartford, CT. Jokinen, E.H. 1992. The Freshwater Snails (Mollusca: Gastropoda) of New York State. New York State Museum Bulletin 482, The New York State Museum, Albany, NY. Nedeau, E.J. 2005. Farmington River Freshwater Mussel Survey. Report submitted to the U.S. Fish and Wildlife Service. Nedeau, E.J. 2006a. Dwarf Wedgemussels (Alasmidonta heterodon) in the Farmington River. Report submitted to the US Fish and Wildlife Service. Nedeau, E.J. 2006b. Freshwater Mussel Survey in Nine Connecticut Streams. Report submitted to the Connecticut chapter of The Nature Conservancy and the Connecticut Department of Environmental Protection. Nedeau, E.J. 2008. Freshwater Mussels and the Connecticut River Watershed. Connecticut River Watershed Council, Greenfield, MA. In Progress. Nedeau, E.J., and J. Victoria. 2003. A Field Guide to the Freshwater Mussels of Connecticut. Connecticut Department of Environmental Protection. Nedeau, E.J., M.A. McCollough, and B.I. Swartz. 2000. The Freshwater Mussels of Maine. Maine Department of Inland Fisheries and Wildlife, Augusta, ME. Peckarsky, B.L., P.R. Fraissinet, M.A. Penton, and D.J. Conklin. 1995. Freshwater Macroinvertebrates of Northeastern North America. Cornell University Press, Ithaca, NY. Smith, D.G. 1995. Keys to the Freshwater Macroinvertebrates of Massachusetts. Second Edition. Published by the author. Thorp, J.H., and A.P. Covich. 1991. Ecology and Classification of North American Freshwater Invertebrates. Academic Press, Inc., San Diego, CA. Trout Unlimited. 2006. A Glass Half Full: The Future of Water In New England. Eastern Water Project, Trout Unlimited.